1. Field of the Invention
The present invention relates generally to systems and methods for inspecting surfaces and, more particularly to systems and methods for inspection and grading of wood railroad ties.
2. Related Art
Railroads are generally constructed on a base layer of compacted, crushed stone material. A layer of gravel ballast rests on top of this stone layer. Crossties are laid in and on this ballast layer, and two parallel steel rails are attached to the crossties with fasteners. The majority of crossties in service are made of wood. Various other materials are used such as concrete, steel, and composite or recycled material in the manufacture of crossties. These alternative material crossties make up a relatively small percentage of all crossties. The crossties maintain the gage or lateral spacing of the rails. The crossties distribute the axle loads from the trains to the ballast layer below the crossties and contribute to the cushioning effect of the entire track structure. Over time, environmental factors can cause the crossties to deteriorate until they must be replaced. Annually, railroads in North America replace up to 2% or more of all wooden crossties. This constitutes several million crossties.
To manage the logistics of crosstie replacement and to quantify the need for new crossties, railroad inspectors attempt to grade the condition of crossties and the fastener system on a regular basis. This grading is most often done with a visual inspection to identify crossties and fasteners that are rotten, broken, split, or worn to an extent that their serviceable life is at its end. The process of visual inspection is quite time consuming. In practice, inspection of the track is performed by an inspector walking along the track to inspect and record the conditions of the crossties and/or fasteners, which are spaced approximately every 20-inches along the track. One particular North American railroad reports that a crew of 3 or 4 men can grade only about 5 to 7 miles of track per day.
Devices for inspecting rail are known in the art, and software for analyzing and organizing data obtained with such devices is known in the art. For example, TieInspect® by ZETA-TECH Associates, Inc. of New Jersey is a computerized crosstie inspection system having a hand held device and software. The handheld device is used by inspectors when walking along the track and surveying the track, and the software is used to analyze and organize the data obtained with the device. However, some prior railroad tie inspection and grading systems and methods have a variety of limitations in their use and present a variety concerns.
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above, thereby providing a system capable of inspecting and grading railroad ties both night and day.